The stability of ballooning modes in tokamaks with internal transport barriers

A. J. Webster; D. J. Szwer; H. R. Wilson

doi:10.1063/1.2032742

The stability of ballooning modes in tokamaks with internal transport barriers

A. J. Webster, D. J. Szwer, H. R. Wilson

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

Modern tokamaks can produce transport barriers (TBs)-localized regions with an increased energy confinement. Previous studies have been unable to examine the stability of internal TBs to radially extended short-wavelength magnetohydrodynamic instabilities ("ballooning modes"), for the usual case with a sheared plasma flow and a magnetic shear that passes through zero near the TB. An established technique is adapted to study this situation, finding instability if (1) there is a low-pressure gradient, and if (2) the nearest "resonant surface" at which a Fourier mode is resonant, is sufficiently close. Surprisingly, flow shear is no more stabilizing than for magnetic shears of order one. This is explained. Without a strongly stabilizing mechanism, ballooning modes will fundamentally limit a TB's radial extent, preventing them from extending across the entire plasma radius.

Original language	English
Article number	092502
Pages (from-to)	1-5
Number of pages	5
Journal	Physics of Plasmas
Volume	12
Issue number	9
DOIs	https://doi.org/10.1063/1.2032742
State	Published - Sep 2005
Externally published	Yes

Funding

Thanks to J. W. Connor and F. L. Waelbroeck for helpful comments. This work was jointly funded by the United Kingdom’s Engineering and Physical Sciences Research Council, and Euratom.

Funders	Funder number
H2020 Euratom
Engineering and Physical Sciences Research Council

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The stability of ballooning modes in tokamaks with internal transport barriers

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